A flash imaging lidar system based on multiple streaks (MS)-streak tube was designed. In the imaging process, the laser beam after expanding was irradiated on the target, and the light reflected by the target was focused on the fiber image transformer through receining antena. The line images transformed from plane image will be coupled to the photocathode of streak tube through an optical taper. The photoelectrons excitated by the line images are accelerated and deflected by the deflecting voltage: And then they were imaged on the phosphor of the streak tube and captured by a CCD camera. In order to remap the line images to area image, the distortion effect of streak tube must be corrected, for it will seriously affect the final image remapping. The reason and effect of the distortion is analyzed in this paper. Distoration of streak image and its effect to image remapping is simulated. The results show that 5% elongated or 0.5% local dip will seriously influence the remapped quality of target image.